Improve handling of ambiguous overstrike sequences. A sequence of _\b_

can either mean an underlined underscore or a bold underscore. This
ambiguity can be 'resolved' by takeing the state of the surrounding text
into account. If surrounded by bold text, the result should probably be
bold and likewise for underlined. less(1) previously only looked at the
preceding text and ul(1) didn't examine the context at all.

tweaks and ok schwarze
ok tb (on a previous version of the diff)

1 files changed, 23 insertions, 12 deletions

diff --git a/usr.bin/less/line.c b/usr.bin/less/line.c
index fe2fe9ff1f5..ebf4b1b5b97 100644
--- a/usr.bin/less/line.c
+++ b/usr.bin/less/line.c
@@ -32,7 +32,6 @@ off_t highest_hilite;		/* Pos of last hilite in file found so far */
 static int curr;		/* Index into linebuf */
 static int column;	/* Printable length, accounting for backspaces, etc. */
 static int overstrike;		/* Next char should overstrike previous char */
-static int last_overstrike = AT_NORMAL;
 static int is_null_line;	/* There is no current line */
 static int lmargin;		/* Left margin */
 static char pendc;
@@ -127,7 +126,6 @@ prewind(void)
 	column = 0;
 	cshift = 0;
 	overstrike = 0;
-	last_overstrike = AT_NORMAL;
 	mbc_buf_len = 0;
 	is_null_line = 0;
 	pendc = '\0';
@@ -515,10 +513,6 @@ store_char(LWCHAR ch, char a, char *rep, off_t pos)
 	char cs;
 	int matches;
 
-	w = (a & (AT_UNDERLINE|AT_BOLD));	/* Pre-use w.  */
-	if (w != AT_NORMAL)
-		last_overstrike = w;
-
 	if (is_hilited(pos, pos+1, 0, &matches)) {
 		/*
 		 * This character should be highlighted.
@@ -808,10 +802,12 @@ do_append(LWCHAR ch, char *rep, off_t pos)
 			if (ch == '_') {
 				if ((a & (AT_BOLD|AT_UNDERLINE)) != AT_NORMAL)
 					a |= (AT_BOLD|AT_UNDERLINE);
-				else if (last_overstrike != AT_NORMAL)
-					a |= last_overstrike;
-				else
+				else if (curr > 0 && attr[curr - 1] & AT_UNDERLINE)
+					a |= AT_UNDERLINE;
+				else if (curr > 0 && attr[curr - 1] & AT_BOLD)
 					a |= AT_BOLD;
+				else
+					a |= AT_INDET;
 			} else {
 				a |= AT_BOLD;
 			}
@@ -825,10 +821,13 @@ do_append(LWCHAR ch, char *rep, off_t pos)
 		/* Else we replace prev_ch, but we keep its attributes.  */
 	} else if (overstrike < 0) {
 		if (is_composing_char(ch) ||
-		    is_combining_char(get_wchar(linebuf + curr), ch))
+		    is_combining_char(get_wchar(linebuf + curr), ch)) {
 			/* Continuation of the same overstrike.  */
-			a = last_overstrike;
-		else
+			if (curr > 0)
+				a = attr[curr - 1] & (AT_UNDERLINE | AT_BOLD);
+			else
+				a = AT_NORMAL;
+		} else
 			overstrike = 0;
 	}
 
@@ -894,6 +893,8 @@ pflushmbc(void)
 void
 pdone(int endline, int forw)
 {
+	int i;
+
 	(void) pflushmbc();
 
 	if (pendc && (pendc != '\r' || !endline))
@@ -904,6 +905,16 @@ pdone(int endline, int forw)
 		 */
 		(void) do_append(pendc, NULL, pendpos);
 
+	for (i = curr - 1; i >= 0; i--) {
+		if (attr[i] & AT_INDET) {
+			attr[i] &= ~AT_INDET;
+			if (i < curr - 1 && attr[i + 1] & AT_BOLD)
+				attr[i] |= AT_BOLD;
+			else
+				attr[i] |= AT_UNDERLINE;
+		}
+	}
+
 	/*
 	 * Make sure we've shifted the line, if we need to.
 	 */